National Geographic: Born of Fire Page #5

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through cracks and

subterranean channels

undergoing substantial

chemical change

as it penetrates the heated

rock layers below

With Dr. Jean-Louis Cheminee

of the French National Center

for Scientific Research

Ballard descend into a recently

active fissure through

which a small flow of seawater

reaches the distant lake

"So this is the sea coming in, right?"

"Yes, by a system of fissures."

"This is where the water

that we see on the other side

of the rift

going into Lake Assal originates from?"

"Yes."

"So it comes in from the sea..."

"...from the sea and crosses the rift

by the fissures inside the mountain..."

"...and out the other side."

"Yes."

"Now, was this fissure

in existence in 1978?"

"Yes, yes."

"It just widened?"

"Just widened."

"Because a lot of these rocks

are just perched

as if they're ready to come down."

"And the car here - just here..."

"Yeah, well, we should move the car."

"So we go like this."

"So we'll go across the..."

"Not across exactly like this. No."

"We go across this area, right?

Now how long will it take us to

get to Assal?

If we went from here all

the way across

went across that flat

desert-like area

how long would it take to get there?"

"Maybe six hours."

"Six hours."

"Yeah, six hours

Terrible road. Six, six and a half."

In torrid heat that reaches more

than 130 degrees Fahrenheit

the water here and in the Rift Valley

is often reduced to a caustic brine

"I'm standing 500 feet below

sea level

near the shore of Lake Assal."

"The ocean is only six miles away

If it weren't for these young lava

flows filling the valley floor

I'd be under water right now

In fact, the ocean is

trying to do that

As rifting develops in the valley

these deep fissures start to form

This lets water travel beneath

the valley

through the fissures

and it can enter Lake Assal

along this outlet

In fact, there are several of

them in the valley."

"At the present moment it's so

hot that most of the seawater

that comes in evaporates

leaving the salt behind

But as rifting continues

more and more water will pour

through these fissure systems

until the sea claims

this entire area

as the ocean penetrates deeper

and deeper into the

continent of Africa."

Here, as in Iceland, the spreading

action creates new crust

Elsewhere, in compensation

the distant edges of an expanding

plate must be destroyed

Outpost of Asia

Japan's island chain bears the shock

of the Philippine

and Pacific Plates as they thrust

beneath the Eurasian Plate

in a massive subduction zone

In the deep ocean trenches off Japan

the aging plates plunge back into

Earth's molten interior

causing powerful disturbances

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